Astrocytes are the most predominant cell species in the brain, and their role is said to be as important as the role of neurons. Embryologically, immature astrocytes are indispensable for formation of functional synapses (Johnson, M. A et al., J. Neurosci. 2007, 27, 3069-3077), and mature astrocytes have a capacity to block synapses and to remove excess transmitters (Rothstein, J. D et al., Neuron, 1996, 16, 675-686). Further, for maintaining nerve fibers, astrocytes play a role as supporting cells. Further, it is suggested that astrocytes may be contributing to maintenance of the function to close the blood-brain barrier by contacting their processes to the blood vessel basement membrane.
On the other hand, it is thought that abnormality of astrocytes is involved in astrocytoma, epilepsy, Alexander disease and neurodegeretative diseases. Therefore, elucidation of these diseased states by analysis of astrocytes is expected.
A method for inducing astrocytes via neural stem cells from pluripotent stem cells such as ES cells or iPS cells has been reported so far (Krencik R, et al., Nat Biotechnol. 2011, 29, 528-534).